A robot can be qualified as humanoid from the moment when it has certain attributes of the appearance and functionalities of a human being such as, for example, a head, a trunk, two arms, two hands, two legs or two feet. Some robots that have only the height of the body can also be considered to be of humanoid type. Humanoid robots are capable of walking or moving around on a platform provided with wheels, of making gestures, with the limbs or with the head. The complexity of the gestures that they are capable of performing is constantly increasing.
These robots are intended to interact with humans and it is necessary to avoid having the gestures of the robots being able to injure the humans around them. More specifically, in the movement of certain articulations of the robot, the latter could pinch human fingers located in proximity. For example, when the arm of a robot approaches its trunk, there is a risk of catching between the arm and the trunk. More generally, the risk of catching exists between two mutually articulated elements of the robot.
Some solutions have been devised to reduce the risk of catching or to limit the consequences thereof. To avoid any catching, it is possible to limit the travel of an articulation by abutment means making it possible to retain a sufficient gap between the elements linked by the articulation concerned. This solution limits the possibilities of the robot by preventing it from certain movements. The anthropomorphism of the robot is then degraded.
To limit the consequences of catching it is possible to reduce the force produced by the actuator moving the articulation concerned. This force reduction also limits the possibilities of the robot which, for example, will no longer be able to lift significant loads. It is possible to limit the force of an actuator only at end of travel, when the two elements approach each other. This limitation entails a complex driving of the actuator. This driving is costly to implement and can be the source of reduced robot reliability.